Say what? Yeah, we were confused too — isn’t the book more of an instruction guide rather than a novel? Yes, but they’re adapting it into a storyline, a la He’s Just Not That Into You.

Lopez is tapped to play Holly, a woman who adopts abroad with her husband due to fertility problems, according to USA Today.

Lopez knows a thing or two about how to play a mother — she told InStyle in 2010 that having her twins changed her life.

“There’s nothing as huge as giving birth to another human being and having to be responsible for another life,” Lopez told the magazine. “There’s you before kids, and there’s you after kids — and they’re not the same you.”

She’s not kidding — the notoriously-busy Lopez slowed down after having her children with Marc Anthony.

“[Parenthood] totally changes your perspective on everything,” Lopez added in that interview. “You don’t come first anymore. There’s somebody else you care more about than yourself.”

Bad Teacher star Cameron Diaz is another big name attached to the Lionsgate project. Filming is scheduled to start in 2012.

Will you see the film version of What to Expect When You’re Expecting?